Current technology offers a variety of techniques to print information, e.g., text and images, onto a receptor, such as paper, Mylar sheet or coated material. Many of the printing techniques are based on the physical transport of a pigment or ink from a reservoir to a receptor in a controlled manner. For example, FIG. 1 illustrates a typical printing system 100, which can be represented by three broad parts: 1) a storage 110 for the pigment, 2) a transport mechanism 120 to deliver the pigment and 3) a receptor 130 to receive the pigment, e.g., a print media.
The storage 110 can be implemented in a number of different manners, e.g., a toner cartridge for a laserjet printer that carries pigment in powder form, an inkjet cartridge for an inkjet printer that carries liquid pigment or a print ribbon in a dot matrix printer.
Similarly, the transport mechanism 120 can be implemented in a number of different manners e.g., the formation and propulsion of droplets (or a spray of droplets) by mechanical means like thermal evaporation, acoustic waves or electrical means. Typically, the droplets exit the storage medium and travel a gap to reach the receptor. An example of droplets (or sprays) propulsion is illustrated by Choi et al., in Society for Imaging Science and Technology, pages 33-35, (1996), which incorporates electro-hydrodynamic (EHD) techniques for printing. An example of droplets formation is also illustrated by Crowley, U.S. Pat. No. 4,220,958 (Ink Jet Electrohydrodynamic Exciter).
However, current printing technology as discussed above are often components of a much larger system or they must be manipulated or serviced by a larger system to perform their primary function, which is printing. For example, the printhead or toner cartridge must reside within a printer. More importantly, the transport mechanism generally requires a significant amount of energy to perform properly, e.g., a high voltage is needed to evaporate droplets onto a paper. This limitation significantly reduces the portability of the printing device.
Therefore, a need exists in the art for a print array that is capable of forming precise droplets that can be dispensed onto a receptor in a high density formation with relatively low power.